Spark plug test bomb



June 4, 1946. A. c. WALL SPARK i LUG 'TEST BOMB Filed Dec. '7, 1945 70 Jij/f 35 36 I -70 l] Hmmm "[mfmg i" zz' 65g ZZ' L @7 z5 r Z5 20 I 69 l sa 0 35u l Vs] i 1f il `i "iz VH; l 52 5 f 47 i i il 82 0 76 I V 49 30// 1 1": 50

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' lemnder C.' lizll 10 Y IgM-izan Patented June 4, 1946 SPARK PLUG TEST BOMB Alexander C. Wall, Indianapolis. Ind., assignor to P. R. Mallory & Co., Ine., Indianapolis, Ind., a corporation oi' Delaware Application December 7, 1943. Serial No. 513,235

(Cl. Z3-37) 8 Claims. l

This invention relates to spark plug testing devices and has for an object to provide a device of the above type having novel and improved details of construction and features of operation.

Another object is to provide a device of the type above indicated having novel and improved means for securing the plugs for testing. u

Another object is to provide simple and dependable means to control the testing pressure.

Another object is to provide a device of the above type which is suited to use for testing in the field and is rapid in operation.

Various other objects and advantages Awill be apparent as the nature of the invention is more fully described.

As a feature of 'the present invention the testing device is made in the form of a cylinder having a head in which the spark plug is inserted for testing. A quick acting linkage is provided to secure the plug in place in an Unthreaded hole in the cylinder head. so that the time and labor required for screwing and unscrewing the plug is eliminated.

The cylinder is provided with a manually operated piston for building up the required testing pressure and vwith a scale cooperating with the operating lever to indicate the pressure. The lever is latched in position to hold the pressure while the plug is being tested, but may be readily released' when the test is completed.

There are available a number of commercial spark plug testing devices which involve either motor-driven pressure pumps or hand-operated pressure pumps, requiring a multiplicity oi hand operations to secure the necessary high pressure to extinguish the spark at the gap of the spark plug. That is due, fundamentally. to the factl that since a pressure of approximately 25 to 30 atmospheres is required, either a multiple stage pump of normal construction or a pump having an extremely large ratio of displacement to clearance volume is required. Mechanical lmulti-stagel pumps require large amounts of power and are not portable. Normally, the use of along strolreV pump involves valves and a mechanical hand application where no source of power may be` available.

Although the novelfeatures which are believed to be characteristic of this invention are pointed out more particularly in the claims appended hereto, the invention may be better understood by referring to the following description, taken 1 provided with a boss 2l. engaging a collar 2l.

mechanism such as a rack and pinion, which is laborious to operate. Y

This invention provides a pump which, by means of a single stroke of the hand through an arc of approximately 120 is capable of producing on the nose of the spark plug a pressure increase of from 25 to 30 atmospheres. This is accomplished by means of a liquid which coversV the piston, and which reduces to zero the clearance in connection with the accompanying drawing in which specific embodiments thereof have been set forth for purposes of illustration. f

In the drawing.

Fig. 1 is a side elevation of a testing device embodying the present invention;

Fig. 2 is a front elevation'with parts in section to show the constructional details; and

Fig. 3 is a detail view illustrating another embodiment of the invention.

lSpeciilc terms are used herein for convenience in referring to various details of theinvention.

It is to be understood, however, that these terms are tor be given aninter'pretation commensurate with the state of theart.

Referring to the drawing more in detail, the testing device is shown in Figs. 1 and 2 as comprising a cylinder Il having a head. H provided with an unthreaded hole i2 suited to receive a sparkplug I2 for testing. Thevspark plug comprises the usual base Il and sleeve Il.

For holding the plug I3 in place in the unthreaded noie l2. a lever u is provided which is' pivoted to an ear 2ll on the cylinder head il. The lever 22 is bifurcated, having parts 22 which span the sleeve Il of the plug. Each part 22' is which is placed over the base I4 of the plug.

For latchlng the lever 22 in position, a latching arm 3l is provided which is pivoted to an ear Il on the cylinder il and'extends upwardly between the parts 22' of the lever 22. A rotating cam 2l is pivoted at the top of the arm 2l and bears z against the parts 22' for holding down the lever 72. "Phe cam 35 it attached to an operating handle 3i by means of which it may be actuated to secure the lever 22 or to release the same..

up to the very electrodes of the spark plug. Since 55 The cylinder lli is provided with a. piston 50. having a. sealing washer 4S, which is slidable axially thereof for building up pressure therein. Said piston '50 is actuated by a. piston rOd 5| which seatsl'in a'socket 48 formed on the'DSton.

The piston rod I isattached by a pin 52 to a crank 53. The crank 53 is carried on a. shaft 56 which extends outwardly through the cylinder wall and carries a bracket 55 to which an operating lever 56 is attached.. The bracket 55 carries a latch 68 having a pawl'tl which is held by va spring 66 in engagement with a rack 62 formed in a bracket 63 attached to the cylinder by suitable means shown as screws 6I. ,The latch 60 is releasable by a rod 65 which extends axially- A layer of liquid 41, such as oil, is provided above the sealing washer 49 to form a liquid piston head which may reduce the clearance toany ldesired minimum value as the oil can accommodate itself to the contour of the cylinder head and spring. Hence an extremely large ratio of displacement to clearance volumeI may be obtained.

'I'he lever 56 is .of a type suited to flex or bend under the load required for exerting the necessary pressure on the piston 50. The amount of deflection of the lever 56 is thus a measure of the pressure within the cylinder Ill. In order to measure this deflection a scale 88 is provided which is mounted onthelever 56 and registers with a pointer 8I on a rod 82 which is mounted in the bracket 5-5. Scale 88 may, ofcourse, be graduated directly in terms of pressure within the cylinder I0. j

` In the operation of this device the plug I3 to be tested is positioned within the hole I2, the collar 28 placed thereon, and the lever 22 brought into holding engagement therewith. 'I'he arm 30 is then brought upwardly between the parts 22' of the lever 22 and the handle 36 is actuated to cause the cam 35 to apply the desired holding pressure to the lever 22. rI'his pressure is sutilcient to cause the plug to seat on the head I I and to eflect a pressure-tight seal suited to withstand the testing pressure. The lever 5 6 is then actuated with sufficient force to build up the desired testing pressure inthe cylinder as indicated by 4. testing pressure may be simply and effectively builtup by manual actuation of the lever 56.`

This pressure may be readily determined and controlled by observing the scale 66 as above described.

In the embodiment shown in Fig. 3 a toggle connection is provided for securing the lever 22 in place. This toggle comprises an arm 85 plvoted to a boss 8'6 formed on the cylinder head l l. A link 81 is pivoted to the arm 85 and carries at its upper end a collar 88 which is held by a spring 89 against the lever 22. A xed'collar 98 is provided to form an operating handle for the link 81 and to Vhold the spring 89 under compression. The arm 85 is provided with a handle 9|. The links 85 and-81 are so arranged that they are on or past center as shown when in operating position, so that they are automatically locked against release. Holding pressure is applied by the spring 89 to the lever 22 for securing the plug I3 in the cylinder head II. The Wall of the-cylinder. I0 forms a stop to limit the movement of the arm 8,5 to holding position.

When it is desired to release the lever 22 the toggle is opened by pulling the arm 85 outwardlyy past its center position. The spring 89 compresses slightly if necessary to permit this movement. Pressure on the collar 88 is thus removed and the link 81 may be swung out of engagement with the lever 22. The piston 56 and the actuat- 'ing mechanism therefor are .similar to those invention is only to be limited in accordance with Y the scope of the following claims.

What is claimed is: l. A spark plug testing device comprising, a cylinder having a head, there being an opening in said head to receive a spark plug for testing,

the pointer 8| on the scale 80. The pawl 6I engages the rack 62 for holding the lever 56 in this position until released. The testing voltage may a then be applied'to the plug I3 in the usual man which releases the pawl 6I from the rack 62 and permits the piston 58 to be retracted. The handle 36 yis then actuated to rotate the cam 35 suiiiciently to remove pressure from the lever 22, whereupon the arm 38 may be withdrawn from registration with the lever 22 to permit the latter to be pivotally rotated so as torelease the plug I3. These operations may then be repeated for testingthe next plug.

It is to be noted that in the above described embodiment the entire testing may be carried out rapidly and eiciently. Only two motions are required for ailixin'g and seating the plug, namely, the actuation of the lever 22 and of the arm 30. This may, of course, be effected in a much shorter time than that normally required for screwing and unscrewing a plug in a cylinder head. The

a piston in said cylinder, a crank for actuating said piston anda lever connected to actuate said crank to build up a predetermined pressure in said cylinder, said lever being bendable under said pressure, and a scale associated withsaid actuating said piston and a lever connected to actuate said crank to build up va predetermined pressure in said cylinder, and means for latching said lever in actuated position. 'i l 3. A spark plug testingdevice comprising, a cylinder having ahead; there being an opening inv said head to receive a spark plug for testing,

ing therewith to latch said lever in' actuated posi-A tion.

4. A spark plug testing device comprising, a

ycylinder having a head, there being an opening v in said head to receive a spark plug for testing, a piston in said cylinder, a crank for actuating said piston, a lever connected to actuatef' said crank to build up a predetermined pressure in said cylinder, said lever being bendable under said pressure, and a scale associated with said lever to indicate the amount of deflection thereof as a, measure of the pressure in said cylinder and means for latching said lever to actuated position.

5. A spark plug testing device comprising, a cylinder having a head, there being an opening in said head to receive a spark plug for testing, a piston in said cylinder, a. crank for actuating said piston, a lever connected to actuate said crank to build up a predetermined pressure in said cylinder, said lever being bendabie under said pressure, and a scale associated with said lever to indicate the amount of deection thereof as a measure of the pressure in said cylinder, a ratchet mounted on said cylinder and a releasable pawl on said lever cooperating therewith to latch said lever in actuated position.

6. A spark plug testing device comprising a cylinder having a head, there being an unthreaded opening in said head to receive a spark plug for testing and means seating said plug in said head to effect a pressure seal for said cylinder, includ ing a pivoted lever having holding means engaging said plug, releasable mechanical means for holding said lever in pressure engagement with said plug, a piston in said cylinder movable for building up air pressure therein for testing, a crank for actuating said piston and a lever con nected to actuate said crank to build up a predetermined pressure in said cylinder. Y

7. A spark plug testing device comprising, a cylinder mounted in a substantially vertical direction having a head, there being an opening ln said head adapted to receive and to hold a spark plug for testing, a piston displaceable in 4said cylinder, a body of non-compressible fluid 6 l o'n said piston constituting a fluid pistonhead therefor, a body of compressible gas above said duid piston head, and means for displacing said piston and the iluid piston head thereon toward said plug to compresssaid gas to a predetermined pressure in said cylinder, said body of n on-'compressible iiuid being adapted to conform to the lower region of the plug and to the upper surface of the piston to reduce clearance to a minimum and to increase the ratio of piston displacement to clearance volume to an extremely high value whereby a high testing pressure may be built up bya single piston displacement.

8. A spark plug testing device comprising, a substantially vertical cylinder having a head, there being an unthreaded opening in said head adapted to receive a spark plug for testing, means for seating said plug in said head to eiect a pressure seal fer-said cylinder including a pivoted lever having holding means engaging said plug and releasable mechanical means for holding said lever in pressure engagement with said plug, a

piston displaceable in said cylinder, a body of non-compressible fluid on said piston constituting a duid piston head therefor, a body of com'- pressible gas above said fluid piston head, and means for displacing said piston and the fluid piston head thereon toward said plug to com-V press said gas to a predetermined pressure in said cylinder, said body of non-compressible iluid being adapted to conform to the lower region of the plug and to the upper surface of the piston to reduce clearance to a minimum and to increase the ratio of piston displacement to clearance volume to an extremely high value whereby va high testing pressure may be built up by a single piston displacement.

ALEXANDER C. WALL. 

